While plant growth-promoting rhizobacteria (PGPR) offer sustainable solutions for managing Ralstonia pseudosolanacearum , the efficacy of many PGPR is often limited by their sensitivity to abiotic stresses, which compromises their field performance. Bacillus velezensis CM5 was identified as a biocontrol and plant growth-promoting rhizobacterium (PGPR) with exceptional environmental resilience. Strain CM5 was isolated from tobacco rhizosphere soil and exhibited strong in vitro and in vivo antagonism against R. pseudosolanacearum , the causative agent of bacterial wilt, achieving a biocontrol efficacy of 41.6%. Greenhouse assays confirmed its capacity to suppress disease and simultaneously enhance plant growth, even under variable temperature and humidity conditions. CM5-treated plants revealed significant reductions in disease index, up to 46.5%, and marked increases in growth parameters, including plant height and biomass. Biochemical assays revealed the elevated activities of antioxidant enzymes (SOD, CAT, POD) and reduced malondialdehyde (MDA) content, indicating induction of systemic resistance. CM5 also produced key hydrolytic enzymes and phytohormones, including IAA, and exhibited nitrogen-fixing and phosphate-solubilizing abilities. Genome sequencing revealed 16 biosynthetic gene clusters encoding antimicrobial compounds, including bacilysin, macrolactin, difficidin, and bacillaene, as well as stress-response genes involved in oxidative stress detoxification, osmoprotection, and thermotolerance. Notably, the strain thrived across a broad range of pH (5.0–8.5), salinity (up to 9% NaCl), temperature (15–40˚C), and drought (up to 15% PEG). These findings present B. velezensis CM5 as a promising, stress-resilient biocontrol strain with multifaceted mechanisms of action. Its dual capacity to suppress R. pseudosolanacearum and enhance plant growth under abiotic stress demonstrates its potential as a reliable candidate for sustainable agriculture and integrated disease management in variable field environments. (a) Isolation and screening of antagonistic and stress-resilient bacteria; (b) Whole-genome analysis of CM5 revealing key genes associated with antibiotic production, plant growth promotion (PGP), stress tolerance, and plant defense; (c) CM5 exhibited strong antagonistic activity against Ralstonia pseudosolanacearum ; (d) CM5 enhanced plant growth under varying environmental conditions
Shan et al. (Wed,) studied this question.